What is a Helicobacter pylori infection?

Definition

Helicobacter pylori is a gram-negative bacillus that causes an
infection of the inner mucus lining of the stomach. It is the primary cause of
gastric ulcers. The prevalence of H. pylori
infection worldwide is more than 50 percent of the population and is much higher
in developing countries.

Causes

H. pylori infections can result from the ingestion of food or liquids contaminated with the bacterium H. pylori, a
spiral-shaped organism with multiple flagella that allow the organism to readily
attach to the stomach mucosa. The organism survives by using the enzyme urease to
break urea down to ammonia and bicarbonate, which neutralizes the strong gastric
acidity. The bacterial secretions stimulate the formation of inflammatory
cytokines, leading to chronic gastritis.
The mucus layer is damaged and thinned by H. pylori secretions of
cytotoxins and by enzymes such as proteases and phospholipases. With the loss of
the protective mucus layer, the strong acids of the stomach attack and damage the
stomach lining, resulting in peptic ulcers. The majority of peptic
ulcer cases in the United States are associated with H. pylori
infections.

Risk Factors

There is a much greater risk of contracting H. pylori infection in developing countries because of unsanitary conditions. Contaminated food and water are primary sources, but other sources include contact with the stool, vomit, or saliva of an infected person.

Symptoms

The majority of H. pylori infections do not cause symptoms. When the infection causes inflammation and ulcers, symptoms can include abdominal pain, nausea, frequent burping, bloating, and weight loss. Immediate medical help is needed if severe abdominal pain, difficulty swallowing, or bloody stools or vomit are experienced.

Screening and Diagnosis

There are three primary ways to diagnosis H. pylori infection.
In endoscopy, a physician threads a flexible tube into the
stomach to remove and examine a tissue sample for the presence of the bacterium. A
breath test involves a patient ingesting a test meal containing radioactively
labeled urea. H. pylori breaks down the urea, forming radioactive
carbon dioxide, which is detected. Finally, a blood test detects the presence of
antibodies against H. pylori, which could
indicate a current or prior infection.

Treatment and Therapy

Treatment usually consists of the administration of three drugs simultaneously
for seven to fourteen days. One of the drugs, omeprazole (Prilosec), is a proton
pump inhibitor (PPI). The other two drugs are antibiotics,
typically clarithromycin and andamoxicillin. The PPIs are necessary to suppress
gastric acid production, which improves the effectiveness of the antibiotics.

Prevention and Outcomes

Although the mode of transmission of H. pylori is not fully understood, what is known is that improved sanitation is an essential preventive measure. A vaccine against the bacillus is under development.

Bibliography

Chey, William D., and Benjamin C. Y. Wong. “American College of Gastroenterology Guidelines on the Management of Helicobacter pylori Infection.” American Journal of Gastroenterology 102 (2007): 1808-1825.

McColl, Kenneth E. L. “ Helicobacter pylori Infection.” New England Journal of Medicine 362 (2010): 1597-1604.

Rosenberg, J. J. “ Helicobacter pylori.” Pediatrics in Review 31, no. 2 (February, 2010): 85-86.

Sultan, Mutaz I., et al. “ Helicobacter pylori Infection.” Available at http://emedicine.medscape.com/article/929452-overview.